Method of and apparatus employing an elongated flexible member for cleaning out obstructions from conduits



March 10, 1953 M J v, O'BRIEN 2,631,113

METHOD OF AND APPARATUS EMPLOYING AN ELONGATED FLEXIBLE MEMBER FORCLEANING OUT DESTRUCTION-S FROM CONDUITS Filed Jan. 13, 1948 PatentedMar. 10', 1953 METHOD OF AND APPARATUS EMPLOYING AN ELONGATED FLEXIBLEMEMBER FOR. CLEANING OUT OBSTRUOTIONS FROM CONDUITS John v. O'Brien,Park Ridge, 111.

Application January 13, 1948, Serial N 0. 2,038

This invention relates to improvements in methods of and apparatus forcleaning out Ohstructions from conduits, of which sewers, drains, pipesand the like are examples, and it consists of the matters hereinafterdescribed and more particularly pointed out in the appended claims.Reference is hereby made to my co-pending application S. N. 2,037, filedon even date herewith, for a method and apparatus of a somewhat similarcharacter.

Cross-reference is also hereby made to my copending application Ser. No.314,716, filed October 14, 1952, entitled Methods of Cleaning outObstructions from Conduits, which relates to somewhat similar subjectmatter.

Heretofore, certain apparatus for this purpose comprised simply aclosely wound helical coil having a working or tool carrying end forengagement with the obstruction in the conduit to be cleaned. It hasbeen customary to associate therewith some means for turning the coilaxially as it is fed through the conduit in the use of the apparatus. Insuch use, when the work end of the coil engages the obstruction and isheld against rotation thereby, continued turning of the remainder of thecoil builds up torque, the magnitude of which is dependent upon thepoweremployed to turn the coil and the resistance to turning which theobstruction supplies. When the torque developed is excessive withrespect to the particular coil, the elastic limit of the wire in thecoils is exceeded and result either in kinking, breaking, or otherwisedamaging the coil.

When torque is applied to the coil in a conduit and it is torsionedbecause of the engagement of the working end with the obstruction, it isthe practice momentarily to retract the coil to loosen the tool or workend in or free it from the obstruction so that the torque causes theworking end to rotate rapidly wit great force against the obstruction.The tool then cuts through the obstruction or hooks onto the obstructionso that the material causing the obstruction may be withdrawn with thewithdrawal of the coil from the conduit, if its character so permits.

To obtain adequate stiffness in such coils the prior practice has beento close-wind the coil under tension to such small diameter as to leavea passageway therethrough no larger than the diameter of the wire ofwhich the coil is composed. In another prior art construction the coilis wound to a larger diameter and provided with a core upon which theconvolutions of the coil are impacted, to afford a firm and permanentgrip thereon.

8 Claims. (01. 134--8) Neither of these practices is entirelysatisfactory for reasons which will be stated later.

Coils for cleaning purposes of this kind are preferably made of arelatively hard steel wire, termed music wire, having a .85 to .95degree carbon content. They are produced either by winding the wire uponan arbor in a lathe or winding the wire in a coiling machine in whichthie' wire is fed with a pushing action against a set of coilin pointsor dies, to form the wire into a coil which leaves the machine in adirection at substantially a right angle to the line of the feed of thewire.

The wire mentioned, which comes in long lengths, is not always uniformin hardness throughout its length, so that certain portions thereof maybe softer than others. Therefore, different portions of the Wire actdifferently in coiling operations.

I from that before coiling. Such crowding of the metal on the inside ofthe convolutions produces fissures and cracks in the coil which reducesthe capacity of the coil to withstand the torque imposed upon it in use.Therefore, such coils kink -or break more easily than would otherwise bethe case. Thus, while coil of smaller diameter afford considerablelongitudinal stifi'ness and have lateral flexibility, they tend to kinkand break prematurely in use and therefore are not wholly satisfactory.

In order to overcome the disadvantages of the smaller diameter coils,attempts have been made to increase the diameter to the extent necessaryto avoid such crowding of the metal. However, when increasing thediameter of the coil,

formed of a given size wire, the capacity of the coil to transmit thetorque necessary to do the work required is reduced. Thus, such coils,when subjected to the torque necessary to remove certain obstructions,will collapse, particularly in those convolutions in which the softermetal is present, thus rendering the coil useless for further work.

Attempts have been made to cure or prevent coils of larger diameter fromcollapsing by employing a central wire or core-around whichthe wire ofthe coil is so tightly wound that relative longitudinal movement cannotoccur between the coil and the embraced core. In use, such coils must beable readily to follow around elbows and other bends in a conduit and insuch manner that no permanent bend or kink will be formed in the coil.However, when a coil, having a core so fixed therein that relativelongitudinal movement cannot take place between the coil and its core,passes around a bend in a conduit the action results in stretching thatpart of the core which is on the outside of the bend. As this stretched.

part of the core cannot return to its normalcondition, a permanent kinkor bow. is developed in the coil, which cannot be straightened out orre-- .quite flexible, have little longitudinal stifiness .and do nothave adequate resistance to torque action. Hence, they tend to collapseprematurely under torque action and when withdrawn from .a conduit, theyopen up between convolutions and cannot be restored to their originalcondition. To prevent such coils from opening up when withdrawing thesame from a conduit, they have in some instances been provided with acentral flexible, but inextensible member of small diameter. Thefunction of this member is merely to. take the pull from the coil. whenwithdrawing. thecoil, from. a conduit to prevent opening of theconvolutions thereof, and it is so small in diameter relative to the.diameter of the coil that. it does not, atv any time, afford internalsupport for the coil.

One of the objects of the present. invention is to provide apparatus ofthis kind which includes as a part thereof an elongated coil having thecharacteristics of a flexible shaft that may be projected work-end firstthrough the bends, elbows and the like of a conduit up to theobstruction therein. Another part of the apparatus is an elongatedflexible core that may be inserted into and longitudinally of the coilfrom its other end toward the work end. The coil and the core are ofsuch diametric cross sectional relation that the core will internallysupport the coil', to better withstand the torsion developed whenturning the coil, with one end engaged with the obstruction, withoutkinking,

breaking or taking on a permanent set.

Also, it is an object of the invention to provide apparatus of the kindabove mentioned wherein the core is: in no manner attached to the coilbut may be withdrawn from the coil for cleaning when necessary and maybe reinserted thereinto .and is then capable of a longitudinal slippingaction within the coil when the latter is not in torsion and which isgripped by the coil for the internal support thereof when in torsion ofa magnitude less than that exceeding the elastic limit of the wire ofthe coil.

The above mentioned objects of the invention,

together with others, along with the advantages thereof, will more fullyappear as the specification proceeds.

In the drawing: Fig. l'is a longitudinal sectional view through the workend of a length. of a coil torming a 4 part of the invention,substantially on a full size scale.

Fig. 2 is a view in side elevation showing the preferred form offlexible core employed with and on a scale greater than that of the coilin Fig. 1.

Fig; 3 is a longitudinal sectional view through the other end of thecoil (opposite the end appearing in Fig. l) and illustrates the mannerin which one end of the core is inserted into the passageway of the coilfor a threading therethrough up to'the work end of the coil appearingin. Fig. 1.

Fig. 4 is a transverse sectional view on the line 4-4 of Fig. 3 but onan enlarged scale, through a part of the coil with the core therein andmore clearly shows the annular space between the external surface of thecore and the internal surface; of the coil when the latter is free oftorque.

Fig. 5 is a longitudinal sectional view through a part of an obstructedconduit such as a drain and shows the coil of the apparatus disposed inthe conduit with its work end engaged with the obstruction therein andwith the core ready for insertion into the other end of thecoil, outsideof said conduit and upon which other end is shown a tool, for turningthe coil and core jointly about their axes in the further part of theoperation of removing said obstruction.

In general, the improved apparatus includes a. closely wound helicalcoil of desired length and a. flexible core that is insertable into andis withdrawable from the longitudinal bore or passageway of the coilwhen the coil is in an untorsioned condition. The diameter of the corewith reference to that of the bore is such that when said core isdisposed within the passageway, a slight clearance onthe order ofDOS/.007 is present therebetween. The coil is provided with a work endwhich is the end first entered into and worked along aconduit until itreaches the obstruction therein. The core, which is in no mannerattached to the coil, is disposed entirely outside the coil. until thelatter has. been worked into the conduit and after which the core isthen inserted into that end of the coil opposite its work end. and whichis then disposed outside of the conduit.

After the coil, with the core disposed in its bore, is located in aconduit with its work end engaged with the obstruction therein, the coilis turned axially either by means of a hand tool or a power tool in theproper direction. Assuming the coil. to be wound. with left hand helix,as indicated inthe drawings, the coil will beturned clockwise, as viewedin Fig. 4, and as indicated by the arrow. With the work end engaged withan. obstruction, theaxial turningof the coil in the direction mentioned,builds up torque in the coil, causing a reduction in diameter to thelimit aiiorded by the slight clearance space between the core and boreof the coil. The coil is thus caused to engage the core throughout itslength and be internally supported and reinforced therebyagainst-premature opening up, breaking or kinking. However, at

the time the coil was being inserted into the conduit, the core was notdisposed therein, and

hence it acted as a relatively free spring readily able to accommodateitself to the tortuous path usually found in conduits from whichobstructions, are to. be removed. While the diameter of the coil isbeing reduced, its length is also being increased, but the space betweenthe core and coil permits the necessary slippage between to 0.95. isknown to the trade as a bright music wire, and well serves the purpose.

coil and core. Hence, neither the coil nor the core is stretched orstrained, so that both return to normal condition after removal from theconduit, provided of course the apparatus be used within the limits forwhich it is designed.

Referring now in detail to that embodiment Of the invention illustratedin Figs. 1, 2 and 3 of the drawing, the improved apparatus includes anouter member or envelope in the form of a long coil having an internalbore or passage designed to receive a flexible core II.

The coil 10 is preferably made of a so-called music steel wire having acarbon content of 0.85 Such wire is obtainable in the market,

The wire has such a cross sectional shape that the sides of ad- 'jacentconvolutions thereof may roll relatively in the bending of the coil.Preferably, therefore,

and as shown, the wire has a circular cross section.

The coil 10, which is preferably produced by die coiling machinesemploying adjustable dies or coiling points which determine the outsidediameter of the coil, includes a relatively long body 22 having arelatively short tool carrying portion '13 at one end. The diameter ofthe body portion 12 of the coil is dependent upon the type of work forwhich the apparatus is to be used. In coils is well adapted for use inthe sewer cleaning art,

especially for the smaller size conduits. The outside diameter of thebody l2 of the coil is dependent upon the diameter of the Wire to beused therefor, the outside diameter of the core H to be used therewith.and the amount of clearance between the coil and core. For a core havingan outside diameter of .217 /.219 and using a wire of .138" for thecoil, such wire is tension wound to such an outside diameter as toafford an overall clearance of .005/.007" between the core and the bodyof the coil. Such a. coil body will have an outside diameterapproximating one-half of an inch. Assuming the core to be centrallydisposed within the coil, there would then be an annular space of0025/0035" between the outside surface of the core and the insidesurface or bore of the coil.

As shown, the portion !3 0f the coil has an inside diameter of about0.60 inch for one-half its length and gradually decreases in diameterfor the other half of its length, to meet the associated end of the body12 of the coil. In said portion 53 of the coil, the convolutions areclosely coiled or wound, but preferably are not in tension, being heatedt a straw color to accomplish this result. Thus, this portion, which isthe leading end of the coil, has more flexibility for bending laterallyof the axes of the coil and is thus better adapted for passage through aconduit having short bends, curves, joints. etc.

The free open end of said portion 13, as shown, has threaded thereinto aplug M, which serves to support an obstruction removing tool and which,in this instance, includes a pair of curved cutting arms. Other forms oftools and work ends may be provided, the form illustrated in the drawingbeing merely one well adapted for the use intended.

The core H is preferably in the form of a flexible member,*such as usedfor the core part in the drives for speed-ometer and dental engines.

-A core which has been found satisfactory comprises a central wire Haand a plurality of multiple spring wire strand layers lib with thestrands in each layer wound in opposite directions. Material of thiskind, which is best illustrated in Fig. 2 and known as speedometer coremay be obtained in the open market in various diameters and no claim isherein made to such material, per se. Preferably the ends of the coreare ground to afford a tip or point lic (see Fig. 3) at each end and thesame may be spot brazed to prevent fraying. Such a tip or point acts asa lead to make easier the threading or working of the core into thecoil.

It will be understood, of course, that the number of layers and thenumbers of strands in each layer and the sizes of wire will vary fordifferent or specific sizes. However, it is believed that a generaldescription of certain sizes of cores will be helpful. Hence, the wirerequirements for three examples or sizes, known as 220 speedometer core,187 speedometer core and speedometer core will be given.

La ea yer No. Angle, Wne Dla.

Degrees l .013 Steel Shaft Wire. 4 39 .013 Steel Shaft Wire. 4. 19 .013Steel Shaft Wire. 4 14 .015 Steel Shaft Wire. 4 11 .017 Steel ShaftWire.

.l25/.1'27 lbs. per/M Feet 32 .13

g Internal Friction Deflection Factor:

Windup Unwind 104 187 speedometer core Helix Layer No Egg Wire Dia.

Degrees Center l .017 Steel Shaft Wire. 1; 4 37 .015 Steel Shaft Wire. 418 .015 Steel Shaft Wire. 4 13 .017 Steel Shaft Wire. 4 10 .017 SteelShaft Wire. 4 10 .022 Steel Shaft Wire.

Actual 0. D. 186/ 188 Weight "lbs. er lltFlTe t Internal Friction -21-!Deflection Factor:

Windup 15 Unwind 31 Wire requirements, 220 speedometer core Helix LayerNo 12 5 Wire Die.

Degrees l .017 Steel Shaft Wire. 4 37 .015 Steel Shaft Wire. 4 18 .015Steel Shaft Wire. 4 14 .017 Steel Shaft Wire. 4 13 .024 Steel ShaftWire. 4 13 .033 Steel Shaft Wire.

Actual O. D. .21 Weight 7/ 2] 9 Internal Friction Deflection Factor:

Win-dun Unwind the core H and using a .138 diameter wire for the coilbody, the coil body wire is wound to provide an overall clearance of.oos"/.0o7" between the outside of the core and the bore of the coil.Assuming the core to be disposed centrally in the bore, there will be aclearance space of between .0025/.0035" between each side of the coreand the associated side of the bore. This clearance space is best shownand indica ed in Fig. 4 by the numeral 55. The body 12 of such a coilwill have an outside diameter of approxlmately .5".

Examples of other more commonly used cores and coils will be given forillustrative purposes. Using 187 speedometer core (Example 2) having anoutside diameter of .l8d"/.188" for the core I! and using .120 diameterwire for the coil body, the coil body wire is wound to provide anoverall clearance of .005" /.00'7 between the outside of the core andthe bore of the coil. Assuming the core is isposed centrally in the borethere will be a clearance space of between .0025"/.G035" between eachside of the core and the associated side of the bore. Such a body (2will have an outside diameter of about .433".

Using 130 speedometer core (Euample 3) having an outside diameter of.l25"/.127 for the core H and using .80 diameter wire for the coil body,the coil body wire is wound to provide an overall clearance of.005"/.(l9'7" between the outside of the core and the bore of the coil.Assuming the core to be disposed centrally in the bore, there will be aclearance space of between .G025/.0035" between each, side of the coreand the associated side of the bore. Such abody i2 will have an outsidediameter of about .292.

Thus, it is assured that the core, though not permanently carried by thecoil, may be readily worked through the coil when disposed in a tortuouspath as is sometimes presented by a conduit. Therefore, the core and thecoil are each in their most freely flexible condition readily to followthe necessary path when workin the coil into a conduit and when workingthe core into the coil without producing a kink or permanent change ofform or either one thereof.

When the coil with the core so disposed therein is positioned in aconduit, as soon as suilicient torque is imposed upon the coil, itconstricts itself to engage the core so the core afiords an internalsupport for the coil against the action of torque tending to fracturethe coil or produce kinks or breaks therein.

In the use of the apparatus, when the core is disposed in the coil, atool, either hand-operated or motor-operated, is used for turning thecoil axially and this in the direction of the arrow in Fig. 4. Thesetools are or may be conventional and are well known in the art. I haveillustrated a motor operated tool it having a chuck 58 to grip and turnthe coil. After the work or tool end of the coil has engaged anobstruction, for example it in Fig. 5, in a conduit 28 and the turningaction is continued in the proper direction, torque is built up in thecoil and this causes the coil to constrict itself in diameter and engagethe core as before explained.

From the above it will be obvious that in using the apparatus disclosedherein, the coil functions substantially as a free flexible spring shaftwhich will readily slide around bends and elbows and past joints in aconduit thereby greatly facilitating insertion of the coil into theconduit. After the. core is disposed in the coil, when the work endengages the obstruction, and turning movement is imparted to the coil inthe manner indicated, from a point outside the conduit, this will causea reduction in the size of. the coil. so as to thereby engage the core,the core acting to provide internal support for the coil. Tests showgreatly improved power transmitting capacity without injury to the coil-It will also be understood that the core extends substantiallythroughout the entire length of the coils when disposed therein. Hence,relative longitudinal movement between thecoil and core can readily takeplace as the coil is reduced in diameter and increased in length in thepreliminary stages of removing an obstruction from a conduit.

Several examples of coil sizes, cores, space be tween core and coil andwire requirements, etc. have been given. While these have been foundsatisfactory in actual use, it should be understood they have been givenas by way of illustration and not necessarily by way of limitation,except where the functioning requires such limitation. For example, theannular space between the core and bore of the coil has been given as ofthe order of .005"/.007" but this may vary, depending upon the size andcharacteristics of the wire of which the coil is formed. The purpose ofthe space between the coil and core is to permit the coil initially tofunction as a substantially free coil with relative slippage betweencoil and core and then when the coil is subjected to torque, whichelongates it and reduces its diameter, to be supported internally by thecore whereby to increase the power transmission capacity of a given coilwhilst maintaining it in good condition. Hence, while the space betweencore and coil. may be more or less than that given, it should never forany particular core-coil combination be so small that the freedom of thecoil in the initial part of an obstruction removing operation isimpaired to the extent that will cause damage to the coil or core whenthe device is used. for its intended purpose and within. the power rangefor which the device is designed.

Again, the space between the core and. coil should not be toogreat-otherwise damage to the. coil will be caused before it engages thecore and is given internal support thereby. Therefore, the maximum spacebetween the core and coil should be such that it can be taken up by thereduction, under torque action, of the coil diameter before the elasticlimit of the particular coll wire is exceeded. Hence, the smallestamount of space between the core and coil, which will afiord freeslippage between coil and core. in the initial part of the operation, isgenerally preferred.

Specification of cores which have been satisfactorily used, have beengiven, but these too are by way of illustration. For example, wire otherthan steel may be used where corrosion is an important consideration.The wire of the core should, however, have spring characteristics sothat when flexed it will return to normal and not take a permanent kinkor set.

Hence, While in describing the invention I have referred in detail tothe form, arrangement and construction of and diameters of the partsinvolved, the same is to be considered only in the illustrative senseand therefore I do not wish to be limited thereto except as may bespecifically set forth in the appended claims.

I claim as my invention:

1. The method of removing obstructions from conduits which consists inpositioning a helically wound flexible wire coil having a longitudinalpassageway therein within a conduit with the work-end of the coiladjacent the obstruction to be-removed therefrom, providing a coremember of less cross sectional diameter than that of said passageway,and disposing the same in said passageway from that end of the coilopposite said work end after said coil has been positioned in saidconduit, and causing the work end of the coil to engage said obstructionwhile turning the coil axially from a point spaced from said work endand in a direction to build up torque in the coil sufficient .to reduceits diameter and cause it to engage and be internally supported by saidcore.

2. The method of removing obstructions from conduits" which consists inpositioning a helically wound flexible wire coil having a longitudinalpassageway therein within a'conduit with the work end of the coiladjacent the obstruction to be removed therefrom, providing a coremember of less cross sectional diameter than that of said passageway,inserting one end of said core into that end of said passageway oppositethe work end of said coil and feeding the core longitudinally along thepassageway ;until said end of said core is disposed in operativeposition relative to said work end of the coil, causing the work end ofthe coil to engage said obstruction while turning the coil axially froma point spaced from said work end and in a direction to build up atorque in the coil sufiicient to reduce its diameter and cause it toengage and be internally supported by said core, before the elasticlimit of the wire of the coil is reached so that said coil and corecoact in the further operation of removing the obstruction from theconduit.

3. A device for removing obstructions from conduits and embodyingtherein, in combination with a helically wound flexible wire coil havinga work end and a longitudinal passageway therein, adapted to be insertedwork end first into a conduit so that said work end is disposed adjacentthe said obstruction in said conduit, a flexible core member having across sectional diameter of such lesser size than that of saidpassageway as to provide a limited clearance space between coil andcore, insertable at any time while the coil is torsionally unstressedend first into said passageway from that end of the coil opposite thework end thereof and workable through said passageway of the coil whilethe latter is disposed in position in said conduit, until said end ofthe core is in operative relation to said work end of the coil, thedimensional characteristics of said coil and core being such that whenthe core is disposed in position in said coil and said coil is held atits work end by said obstruction and is turned axially from a pointspaced from the work end and in a direction to build up torque therein,said coil will reduce in diameter to such an extent that it will engageand be internally supported by the core before the elastic limit of thewire of the coil is exceeded.

4. A device for removing obstructions from conduits and embodyingtherein, in combination with a helically wound flexible wire coil havinga work end and a longitudinal passageway therein, adapted to be insertedwork'end first into a conduit so that said work end is disposed adjacentthe said obstruction in said conduit, a flexible core member comprisinga center wire and a plurality of layers of multiple wire strands woundtherein and which core has a cross sectional diameter of such lessersize than that of said passageway as to provide a limited clearancespace between coil and core and insertableat any time while the coil istorsionally unstressed end first into said passageway from that end ofthe coil opposite the work end thereof and workable through saidpassageway while the latter is disposed in position in said conduit,until said end of the core is in operative position relative to the workend of the coil, the dimensional characteristics of said coil and corebeing such that when the core is disposed in position in said coil andsaid coil is held at its work end by said obstruction and is turnedaxially from a point spaced from the work end and in a direction tobuild up torque therein, said coil will reduce in diameter to such anextent that it will engage and be internally supported by the corebefore the elastic limit of the wire of the coil is exceeded.

5. A device for removing obstructions from conduits and embodyingtherein, in combination with a helically wound flexible wire coil havinga work end and a longitudinal passageway therein, adapted to be insertedwork end first into a conduit so that said work end is disposed adjacentthe said obstruction in said conduit, a flexible core member comprisinga center wire and a plurality of layers ofmultiple wire strands woundtherein and which core has a cross sectional diameter less than thatoftsaid passageway, providing a clearance of DOE/.007 between the coiland core, said core being insertable at any time while the coil istorsionally unstressed end first into said passageway from that end ofthe coil opposite the work end thereof and workable through saidpassageway while the latter is disposed in position in the conduit untilsaid end of the core is in operative position relative to the work endof the coil, the dimensional characteristics of said clearance beingsuch that when the core is disposed in position in said coil and saidcoil is held at its work end by said obstruction and is turned axiallyfrom a point spaced from said work end and in a direction to build uptorque therein, said coil will reduce in diameter to that extent that itwill engage and be internally supported by the core before the elasticlimit of the wire of the coil is exceeded.

6. Apparatus for removing obstructions from conduits comprising anelongated helical flexible spring wire coil having a longitudinalpassageway therein and a dimensionally related core member for conjointuse therewith in an obstruction removing operation, said core memberbeing movable as an entity and embodying a plurality of layers ofhelically wound strands, the cross sectional dimension of the core beingof such lesser size than at least the major part of the passageway inthe coil when torsionally unstressed as to provide a limited clearancespace between the core and coil when the core is positioned within thecoil and entirely throughout the length of the core within coil, aidlimited clearance space permitting movement of the core longitudinallyin both directions while the coil is torsionally unstressed, saidclearance space being such that when the coil is held at one end andturned axially from a point spaced from said end the limited clearancespace is taken up by a reduction of coil diameter until the coil engagesand is internally supported by the core before the elastic limit of thecoil wire is exoeeded.

'7. Apparatus for removing obstructions from conduits comprising anelongated helical flexible spring coil having a longitudinal passagewaytherein and a dimensionally related core member for conjoint usetherewith in an obstruction removing operation, said core member beingmovable as an entity and embodying a plurality of 'layers of helicallywound strands, the cross sectional dimension of the core being of suchlesser size than at least the major part of the passageway in the coilwhen torsionally unstressed as to provide a limited clearance spacebetween the-core'and coil when the core is positioned within the coiland entirely throughout the length of the core within coil, said limitedclearance space permitting movement of the core longitudinally in bothdirections while the coil is torsionally unstressed, the cross sectionalsize of :the coil wire being at least several times .the cross sectionalsize of the individual strands of which the-core is :composed, saidclearance space being such that when the coil is held .at one end andturned axially from a point spaced from said end the limited clearancespace is taken up by areduction of coil diameter until the coil engagesand is internally supported by the core before the elastic limit of thecoil wire is exceeded.

8. A device for, removing obstructions from conduits comprising ahelically wound flexible spring wire coil vhaving a longitudinalpassageway therein, said .coil having ends at least one of which isa'work endpa flexible spring wire core disposed within said passagewayand of such lesser diameter than that of the passageway as to provide aclearance space between coil and core throughout at least amajor portionthereof when the coil "is torsionally unstressed, which clearance spaceis of such limited size that it can be taken up by torsional reductionof cell diameter before exceeding the elastic "limit of the coil wire,and means at least at one end of the coil detached from :but preventinglongitudinal movement of'the core as a-whole beyond said one end of thecoil, thereby providing vfor the free slidable :relative movementbetween soil and core when the .coil is 'ltorsionally unstressed wherebywhen the coil .is held against turning movement at the work end and :isturned :axially .from :a point spaced from said end, and in a directionto :build up :sufiicientitorsional stress, the diameter of the coil willhe reduced, thereby taking :up the limited clearance between coil andcore and causing the coil to be :internally supported by the core insuch reduced portion of the coil.

JOHN V. OBRIEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name :Date

887,160 Webb May 12, 1908 1,154,369 Browning Sept. 21, 1915 1,600,373Stremel Sept. .21, 1926 2,006,333 Angeli :et a1. July 2, 1935 2,244,735Silverma-n June 10, 1941 2,336,334 Zublin .Dec. 1'1, 1943

1. THE METHOD OF REMOVING OBSTRUCTIONS FROM CONDUITS WHICH CONSISTS INPOSITIONING A HELICALLY PASSAGEWAY THEREIN WITHIN A CONDUIT WITH THEWORK END OF THE COIL ADJACENT THE OBSTRUCTION TO BE REMOVED THEREFROM,PROVIDING A CORE MEMBER OF LESS CROSS SECTIONAL DIAMETER THAN THAT OFSAID PASSAGEWAY, AND DISPOSING THE SAME IN SAID PASSAGEWAY FROM THAT ENDOF THE COIL OPPOSITE SAID WORK END AFTER SAID COIL HAS BEEN POSITIONEDIN SAID CONDUIT, AND CAUSING THE WORK END OF THE COIL TO ENGAGE SAIDOBSTRUCTION WHILE TURNING THE COIL AXIALLY FROM A POINT SPACED FROM SAIDWORK END AND IN A DIRECTION TO BUILD UP TORQUE IN THE COIL SUFFICIENT TOREDUCE ITS DIAMETER AND CAUSE IT TO ENGAGE AND BE INTERNALLY SUPPORTEDBY SAID CORE.
 3. A DEVICE FOR REMOVING OBSTRUCTION FROM CONDUITS ANDEMBODYING THEREIN, IN COMBINATION WITH A HELICALLY WOUND FLEXIBLE WIRECOIL HAVING A WORK END AND A LONGITUDINAL PASSAGEWAY THEREIN, ADAPTED TOBE INSERTED WORK END FIRST INTO A CONDUIT SO THAT SAID WORK END ISDISPOSED ADJACENT THE SAID OBSTRUCTIOIN IN SAID CONDUIT, A FLEXIBLE COREMEMBER HAVING A CROSS SECTIONAL DIAMETER OF SUCH LESSER SIZE THAN THATOF SAID PASSAGEWAY AS TO PROVIDE A LIMITED CLEARANCE SPACE BETWEEN COILAND CORE, INSERTABLE AT ANY TIME WHILE THE COIL IS TORSIONALLYUNSTRESSED END FIRST INTO SAID PASSAGEWAY FROM THAT END OF THE COILOPPOSITE THE WORK END THEREOF AND WORKABLE THROUGHT SAID PASSAGEWAY OFTHE COIL WHILE THE LATTER IS DISPOSE IN POSITION IN SAID CONDUIT, UNTILSAID END OF THE CORE IS IN OPERATIVE RELATION TO SAID WORK END OF THECOIL, THE DIMENSIONAL CHARACTERISTICS OF SAID COIL AND CORE BEING SUCHTHAT WHEN THE CORE IS DISPOSED IN POSITION IN SAID COIL AND SAID COIL ISHELD AT ITS WORK END BY SAID OBSTRUCTION AND IS TURNED AXIALLY FORM APOINT SPACED FROM THE WORK END AND IN A DIRECTION TO BUILD UP TORQUETHEREIN, SAID COIL WILL REDUCE IN DIAMETER TO SUCH AN EXTENT THAT ITWILL ENGAGE AND BE INTERNALLY SUPPORTED BY THE CORE BEFORE THE ELASTICLIMIT OF THE WIRE OF THE COIL IS EXCEEDED.